Assessment of the Water Quality of the Mirim Lagoon and the São Gonçalo Channel Through Qualitative Indices and Statistical Methods

Abstract

The Mirim Lagoon is one of the most important freshwater lagoons in the Brazilian territory, connecting the Patos Lagoon through the Sao Goncalo Channel. With the diversification of the uses of rivers, watersheds, and lakes, sustainable management and management of these ecosystems are extremely relevant. For this reason, the monitoring of these environments is of great importance. In view of the above, the water quality index (WQI), the trophic state index (TSI), and statistical methods are tools that enable rapid assessment of water characteristics regarding pollution sources, expressing its quality in a single value, which facilitates understanding. Thus, this study aims to evaluate the water quality of the Mirim Lagoon and the Sao Goncalo Channel through these methods. With the proposed methods, it was possible to observe that the Mirim Lagoon and the Sao Goncalo Channel suffer strong influence from agricultural activities and the release of untreated effluents into their beds, causing the deterioration of these water resources. Despite this, for the most part, the collection points had a good WQI and TSI varying between quality ranges 1 and 3. Furthermore, the importance of statistical methods to assess the studied parameters is highlighted, since they promote more accurate results.